While no normative values exist for mesenteric rSO2 in premature infants, recent studies have explored NIRS use in determining gut hypoxia and ischemia (14). Abdominal NIRS was used to detect alterations of intestinal rSO2 and perfusion in premature piglets that developed NEC (15). In a prospective cohort study of 40 neonates with medical or surgical acute intraabdominal pathology, a cerebro-splanchnic oxygenation ratio (CSOR) of less than 0.75 predicted gut ischemia with 90% sensitivity (16).